Mineral: |
Kaolinite |
Reference: |
AJW97 |
SCM Type: |
CC - Constant Capacitance
(C1: 2.1 F/m2) |
Ionic Strength: |
0.005 mol/L of
KNO3
|
Site Type: |
»Al-OH |
PZC: |
|
pK1: |
3.24 |
pK1°I=0 (Conversion to I = 0): |
3.21 |
pK12.31 nm−2 (normalized): |
3.16 |
pK2: |
7.15 |
pK2°I=0 (Conversion to I = 0): |
7.12 |
pK22.31 nm−2 (normalized): |
7.23 |
Site Density in nm-2: |
1.9271 |
Original Site Density: |
3.2 µmol / m² surface
|
Solid/Liquid Ratio in g/L: |
6.38 |
pH Range: |
3.5-9 |
Temperature in K: |
298.15 |
Method for Site Density: |
Sorption Isotherms |
Method for Protolysis: | Potentiometric Titration |
Fit Method: | FITEQL |
Comment: |
2 distinct populations of adsorption sites on the kaolinite surface: relatively sparse ion-exchange sites on the siloxane faces XH (significant adsorption between pH 3 and 5) and more closely spaced variable-charge hydroxyl sites SOH (probably aluminol groups at crystal edges); total SSD=5.5µmol/m^2: {SOH} = 3.2+-0.1 µmol/m2 and {X-} = 2.3+-0.1 µmol/m2; pK values for {SOH} sites; cited in [AJW98]; cation exchange on the siloxane faces =SiH + K+ = =SiK + H+: Titration with 0.1M HNO3 and 0.1M NaOH; 25°C |
|